Modern adhesive tapes and flexible sheet materials are now mass-produced with a very high degree of uniformity, both in terms of thickness and color or transparency. As a result, without a dispenser, it is often very difficult to find the edge of such materials, particularly if allowed to fall back onto the outer surface of the roll once cut or tom for use.
Many different types of tape exhibit this frustrating problem, including mending tapes and packing tapes, particularly the clear varieties. One clever solution to this problem is disclosed in U.S. Pat. No. 3,537,578, simply entitled “TAPE.” According to this patent, a piece of tape includes a continuous marking imprinted thereon, which preferably extends diagonally from one corner of the tape to the other, or, alternatively, a wavy line is used which forms part of the repeating pattern. In both cases, after the tape is formed into a roll, the free end of the tape can be plainly visualized because the continuous line is broken and separated. It is clear from the disclosure of this patent, that the concept is not intended for use with transparent tapes, since only “insulating tapes” are specifically mentioned. If applied to transparent tapes or other materials, the line might be undesirable, particularly if the layers of the material are substantially transparent.
Although certain tape structures make use of fluorescence, its use is for surface highlighting as opposed to edge-finding. Using U.S. Pat. No. 4,913,946 as an example, which is entitled “FLUORESENCE ADHESIVE TAPE FOR USE AS A HIGHLIGHTER,” fluorescent ink is applied to one face of the transparent film or support base, having a layer of low-tack adhesive, allowing the removal of the material from library books, and so forth, without damaging the printed matter. U.S. Pat. No. 5,693,394, entitled “PRESSURE-ACTIVATED FLUORESCENT MARKING TAPE,” includes an adhesive fluorescent coloring layer coated on a carrier, wherein, upon application of pressure on the back of the carrier, the coloring layer is transferred to a substrate. U.S. Pat. No. 5,707,482, entitled “REMOVABLE HIGHLIGHTING TAPE,” adds the feature of a dispenser having a cutting edge, further evidence that the prior art does not teach or consider the use of fluorescence or other optically-activated materials as an edge-finding feature. It is a notable, and required, feature of these highlighting tapes that they are highly colored, and this precludes their use in many applications.
Although at least one patent discloses the use of colored edges for edge-finding, this is not disclosed for use with newly-formed edges, but, rather, for use in conjunction with existing edges which are not torn or cut. This particular reference is U.S. Pat. No. 5,340,629, entitled “ADHESIVE TAPE,” which is directed to the translucent material having an adhesive-free colored edge, enabling a health-care worker to visually discern and manipulate a tape edge even when using protective gloves. Thus, any mechanism tending to make newly formed edges on tapes or other materials more visually apparent would be welcomed by users thereof.